Path: ...!2.eu.feeder.erje.net!3.eu.feeder.erje.net!feeder.erje.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: Terje Mathisen <terje.mathisen@tmsw.no>
Newsgroups: comp.arch
Subject: Re: Continuations
Date: Fri, 19 Jul 2024 20:55:47 +0200
Organization: A noiseless patient Spider
Lines: 21
Message-ID: <v7ecrj$33vqv$1@dont-email.me>
References: <v6tbki$3g9rg$1@dont-email.me>
 <47689j5gbdg2runh3t7oq2thodmfkalno6@4ax.com> <v71vqu$gomv$9@dont-email.me>
 <116d9j5651mtjmq4bkjaheuf0pgpu6p0m8@4ax.com>
 <f8c6c5b5863ecfc1ad45bb415f0d2b49@www.novabbs.org>
 <7u7e9j5dthm94vb2vdsugngjf1cafhu2i4@4ax.com>
 <0f7b4deb1761f4c485d1dc3b21eb7cb3@www.novabbs.org>
 <v78soj$1tn73$1@dont-email.me> <v7dsf2$3139m$1@dont-email.me>
 <277c774f1eb48be79cd148dfc25c4367@www.novabbs.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Injection-Date: Fri, 19 Jul 2024 20:55:48 +0200 (CEST)
Injection-Info: dont-email.me; posting-host="7a90b425738fe350d193c07393a44b0c";
	logging-data="3276639"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX188cMRQzqJpje7zMpoMH+PV9tePyzPAdnSk9oU5AtrchQ=="
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101
 Firefox/91.0 SeaMonkey/2.53.18.2
Cancel-Lock: sha1:vLyeHNVvZzXDSbbUKQyP8v19hkM=
In-Reply-To: <277c774f1eb48be79cd148dfc25c4367@www.novabbs.org>
Bytes: 2456

MitchAlsup1 wrote:
> On Fri, 19 Jul 2024 14:16:01 +0000, Terje Mathisen wrote:
>> Back when I first looked at Invsqrt(), I did so because an Computation
>> Fluid Chemistry researcher from Sweden asked for help speeding up his
>> reciprocal calculations (sqrt(1/(dx^2+dy^2+dz^2))), I found that by
>> combining the 1/x and the sqrt and doing three of them pipelind together
>> (all the water molecules having three atoms), his weeklong simulation
>> runs ran in half the time, on both PentiumPro and Alpha hardware.
> 
> I, personally, have found many Newton-Raphson iterators that converge
> faster using 1/SQRT(x) than using the SQRT(x) equivalent.

Yeah, that was eye-opening to me as well, to the level where I consider 
the invsqrt() NR iteration as a mainstay, it can be useful for both sqrt 
and 1/x as well. :-)

Terje

-- 
- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"